It’ll take a long time, likely a generation or two, but you can completely shut down organization’s such as Fox News and other faux news sites by investing in education. You’ll need to teach a generation about how to apply critical thinking skills so that they can discern a reliable source of news from an outlet that merely repeats and reinforces points of view.
You’ll also need to work on reshaping society to value knowledge over belief. Expect a lot of resistance from that one — from the left and the right. It’s much easier to believe something than to understand it and human nature tends toward the path of least effort.
Only after you’d dismantled our faith-based approach to reality will you have a society that’s been inoculated against propaganda and prefers to think for itself.